1. Field of the Invention
This invention relates to the structure of a solid state image pickup device, and more particularly to an interpolating method for heightening the pseudo-resolving power of the device in the vertical rows of image sensing elements.
2. Description of the Prior Art
The solid state image pickup devices having light-to-charge converting 3 charge-accumulating portions and charge transfer portions, for example, charge coupled device (CCD) and bucket bridage device (BBD) have their resolving power for the object image formed on the one-dimensional or two-dimensional sensing surface depending upon the number of light receiving elements constituting a unity of image sensing line or area. To achieve an increase in the apparant resolving power with a limited number of light receiving elements, there is known, among others, a method of interpolating the outputs of the light receiving elements (resolution cells). For example, U.S. Pat. No. 4,148,059 discloses a device in which the interpolation of the outputs of the resolution cells is made by providing a memory for storing the outputs of the resolution cells a, delay means, a difference amplifier, an integrator and associated circuits as arranged outside the image sensor. These components are of large scale and, therefore, had the drawback that in actual practice it is very difficult to fabricate the image sensor and the interpolating means in one chip. This drawback becomes serious when the points of the image in the vertical direction are interrelated, because the number of delay means must be equal to the number of columns of resolution cells. Delay means and other associated means are very expensive and create an additional drawback in that the complexity of structure of the device is considerably increased.